Trismus is reduced mouth opening that results from trauma, infection, a sequaele of surgery, muscle spasm of the muscles of mastication, rheumatoid and osteo-arthritis, tumors, tendonitis or internal derangment of the jaw joint, etc. A person afflicted with trismus is not able to fully open their lower jaw. This is problematic in that, often, access to the interior of the afflicted person's mouth and throat is necessary to effectively treat the cause of the affliction. Approximately 75,000 to 100,000 person in the United States require treatment for this ailment annually.
Additionally, there are other occasions, such as during an examination or any procedure performed with or without general or local anesthesia, when the patient's mouth must be propped open.
There are several devices of which I am aware which are provided for dilating and/or for propping open a human mouth. The Heister mouth prop consists of a pair of arms which can be adjusted to an open position by a hand adjustable threaded screw. The ends of the arms are serrated to grip the teeth or a sleeve which can be placed over the ends. The Maunder screw jaw spreader is a spiral plug which is inserted between the patient's teeth and hand adjusted to prop open the mouth. Also, there are several mouth-gag devices of the hemostat variety such as the Hu-Friedy Molt, Ace Molt, Ace Doyen Collin Molt, Ace Doyen Jansen Molt and Ace Denhardt Mouth Gags. In addition, the Dingman Mouth Gag is a frame with coiled springs, tongue depressors, cheek retractors and movable tooth hooks which is positioned in front of the mouth. The McIvor Mouth Gag is a substantially triangular frame with an attached adjustable tongue depressor. The Davis-Boyle Mouth Gag is a reverse "C" shaped frame with an adjustable tongue depressor. In U.S. Pat. No. 2,061,936 issued to Engelfried, a mouth prop is disclosed that is inserted between a patient's teeth. This device includes a threaded bolt that carries a pair of bars thereon that, carrying tooth engagement means thereon, are linearly movable to prop a mouth open. In U.S. Pat. No. 2,182,390 issued to Reardon, a surgical device is disclosed for propping open the mouth of a patient, so as to permit access to and illumination of the area in back of the nose and above the palate.
While being useful for their purpose, both of these patented devices have particular drawbacks, especially where the patient is afflicted with trismus. In particular, in both devices, as well as in all other devices of which I am aware, the jaw supporting portions move away from and towards one another in a straight linear fashion. Unfortunately, the mandible does not move in such a linear fashion. The jaw joint is a ginglimoarthroidial joint and, as such, moves in a sliding pivotal articulation (where the lower jaw joins the skull), such that the lower jaw pivotally moves away from and towards the skull in a substantially arcuate path. Thus, if the devices disclosed in Engelfried and Reardon would be utilized to open a jaw afflicted with trismus, the tooth engaging portions thereof, while moving linearly, would slip or ride over the teeth of the jaw, which moves arcuately. Such an arrangement can result in breaking and/or other damage occurring to the teeth and/or jaw of the patient.
Thus, it can be seen that there remains a need for a device for dilating and/or propping open a jaw which has tooth (or jaw) engaging portions that pivot outwardly from and towards one another, moving in a substantially arcuate path.